Residual yeast from brewing operations and yeast produced as baker's yeast have long been used in foods as a source of vitamins, minerals, and protein. The levels of dried yeasts used in food products has never generally exceeded more than 5% because dried food yeasts have no functional value for food processing, and, at higher levels, contribute a distinct taste to the food product.
Extracts of yeast have long been used as a source of flavor. Extracts of yeast are sometimes classified into autolysates, plasmolysates, and hydrolysates according to their method of preparation. Hydrolysates are prepared by the controlled cooking of yeast in acid solution. Plasmolysates are prepared by extracting the cellular materials from the yeast cell with high concentrations of salt, sugar, or certain acetate esters. Autolysates are prepared by inducing the self-digestion of the cytoplasmic materials in the whole cell followed by recovery of the solubilized material. By any method, an insoluble residue is also obtained. This insoluble residue contains the extracted and washed yeast cell debris. This debris, which is usually discarded as a waste product contains the walls of the yeast cell, and usually protein, nucleic acid, and lipid components.
We have discovered a method of reclaiming a valuable food product from this cellular debris. This product has bland flavor, and unique functional characteristics. We call this product glycan.
One of the primary functional characteristics of this product is its ability to hold water and give thickening properties to aqueous food system. We have further discovered that the addition of this product to liquid food systems gives the food product a "fat-like" mouthfeel even when these products contain little or no fat. This is very useful in formulating low-calorie products. The product obtained from the insoluble residues of yeast has all of the desirable attributes of the product described in copending application of Sucher, Robbins, Sidoti, Schuldt and Seeley entitled YEAST GLYCAN AND PROCESS OF MAKING SAME Ser. No. 310,452 filed Nov. 29, 1972, U.S. Pat. No. 3,867,554 issued Feb. 18, 1975. The glycan described in that application and the glycan described herein both consist of the fragmented cell walls of yeast, but are obtained by different processes.
We have discovered that a satisfactory glycan preparation can be obtained from the insoluble residue remaining from the autolysis process. This insoluble residue can be obtained from the autolysis of baker' s yeast, brewer' s yeast, or a mixture thereof.